Growth And Characterization Of Lead Selenide Thin Films And Nano-particles

Lead selenide is a kind of narrow band-gapⅣ-Ⅵsubgroup compound semiconductor, which is widespread used in infrared detection field. The infrared detectors made from lead selenide thin films have high quality and high sensitivity. Lead selenide nano-particles have some special characters, and will widen application realm. This article presents preparation of lead selenide thin films with aerosol-assisted chemical vapor deposition (AACVD) method and preparation of lead selenide nano-particles with colloidal method, and then presents the characterization of prepared thin films and nano-particles.Lead selenide thin films were deposited by AACVD method at the temperature of 300-500℃for 90 min, using lead acetylacetonate and TOPSe as precursors, using acetylacetone as solvent, and using nitrogen as protection atmosphere (120 sccm). The deposited films are identified to be the poly-crystal lead selenide and have cubic crystal structure by X-ray diffraction method. SEM images show that the films are composed with nano-size conformations, and the films deposited at 400℃are wholly composed of nano-towers and the films deposited at 500℃are built up with nano-rods. The ratios of Pb and Se in the films are approaching 1 when the deposition temperature rising up to 500℃. Thicknesses of films change fast when deposition temperature rising, from 53 nm at 300℃to 4020 nm at 500℃. The resistivity of films become larger when the temperature rising at the range of 20-200℃. The optical spectrum shows that the deposited films have two step absorbance mechanics at the wavelength range of 2.5-25μm.Lead selenide nano-particles are grown from the same precursors, lead acetylacetonate and TOPSe, at the temperature of 160-210℃for 10-30 min using oleic acid as capping ligand and using phenylate as solvent. The XRD patterns show that the products have cubic crystal structure too. Sizes of these nano-particles are between 21.65-38.93 nm, calculated by Scherrer equation with XRD patterns. With lower reaction temperature, shorter reaction duration and thinner capping ligand density, the size of the nano-particles will be smaller. And TEM images show that two forms of nano-particles are grown, one is normal sphere shape and the other is octahedron shape.